Mechanised dental instrument

ABSTRACT

The invention relates to a mechanized dental instrument consisting of an active part ( 2 ) and a sleeve ( 3 ) arranged on the end opposing said active part, said sleeve ( 3 ) being provided with a rotating drive means ( 4 ) that can directly engage, in the assembly position, in the head of a handpiece, with a rotating drive means located upstream of the head of the handpiece. The invention is characterized in that the drive means ( 4 ) is produced from a flat metallic piece which is fixed, especially by being slid over the axle ( 2   a ) of the active part ( 2 ), and is provided with at least one opening ( 5 ) that is shaped in such a way as to enable the circulation of the plastic material forming the sleeve ( 3 ) during the molding over said axle ( 2   a ) and to thus ensure the connection of the rotating drive means on the axle ( 2   a ).

The present invention relates to a mechanized dental instrument, in particular an endodontic instrument.

Generally, mechanized dental instruments consist of an active part and of a sleeve arranged at the end remote from said active part. Said sleeve of the dental instrument is provided with a rotary drive means which, in a position mounted in a head of a handpiece, is able to mesh directly with a rotary drive means located upstream of the head of the handpiece, such as is described in particular in patent application FR 2 759 574 filed by the present Applicant.

Such dental instruments are generally made partly of plastic overmolded on the active part. The major disadvantage of such a production method is the resistance of the teeth of the pinions at substantial torques, leading either to fracturing or premature wear of said teeth.

The object of the invention is to make available a mechanized dental instrument with which all or some of the aforementioned disadvantages can be remedied.

To this end, the subject of the present invention is a mechanized dental instrument consisting of an active part and of a sleeve arranged at the end remote from said active part, said sleeve of the dental instrument being provided with a rotary drive means which, in a position mounted in a head of a handpiece, is able to mesh directly with a rotary drive means located upstream of the head of the handpiece, characterized in that the drive means is produced from a flat metal piece which is fixed especially by being slid over the axle of the active part, said piece being provided with at least one opening shaped in such a way as to permit circulation of the plastic material forming the sleeve during the phase of overmolding on said axle and thus to ensure the connection of the rotary drive means on the axle.

According to an alternative embodiment, said opening is formed by the combination of flats formed on the axle of the active part and the central orifice of the drive means, permitting introduction of the axle through the latter.

According to an advantageous characteristic, the drive means is produced from a flat piece whose toothing is formed by cutting and then, if appropriate, by bending.

The characteristics of the invention which have been mentioned above, and others too, will become clearer from reading the following description of an illustrative embodiment with reference to the attached drawings, in which:

FIG. 1 is a cross-sectional view of a mechanized dental instrument according to the present invention,

FIG. 2 is a view similar to FIG. 1, showing an alternative embodiment,

FIG. 3 is a cross-sectional view of a pinion for a mechanized dental instrument,

FIG. 4 is a cross-sectional view of a mechanized dental instrument showing a second illustrative embodiment,

FIG. 5 shows a third alternative embodiment of the dental instrument according to the invention,

FIG. 6 is a cross-sectional view of the dental instrument according to the invention in a fourth alternative embodiment.

A mechanized dental instrument 1 for endodontics is depicted in FIG. 1. This instrument is traditionally made up of an active part 2 and of a sleeve 3 arranged at the end remote from said active part 2, the latter being designated as “axle” 2 a in the remainder of the description.

This sleeve 3 of the dental instrument 1 is provided with a rotary drive means 4 of the pinion type which, in a position mounted in a head of the handpiece, meshes directly with a rotary drive means located upstream of the head of the handpiece.

According to the present invention, the drive means 4 is produced from a flat metal piece which is fixed especially by being slid over the axle 2 a, said piece being provided with at least one opening 5 shaped in such a way as to permit circulation of the plastic material forming the sleeve 3 during the phase of overmolding on said axle 2 a and thus to ensure the connection of the rotary drive means on the axle 2 a.

As can be seen from FIG. 1, the metal part 4 forming the drive means is provided with four uniformly distributed orifices 5 permitting circulation of the plastic during overmolding of the sleeve 3 on the axle 2 a of the active part.

According to an alternative embodiment shown in FIG. 2, the axle 2 a of the active part 2 comprises flats 6 such that, after positioning of the metal piece, it is possible to overmold the formation of said sleeve in such a way that the plastic encompasses the flats 6 via the openings 5 and thus ensures connection in terms of rotation.

It should be noted, advantageously, that the metal part 4 is produced from a flat piece, then by cutting the teeth forming the drive means, thus reducing the cost compared to a conventional solution, as can be seen in FIG. 3.

In addition, when it is necessary to ensure driving in rotation by means of a conical gear, the toothing of the pinion is deformed in such a way that it is raised or lowered relative to its core.

According to a second alternative embodiment of the invention shown in FIG. 4, the active part 2, namely the dental tool, extends all the way through the sleeve 3 of the dental instrument 1.

The alternative embodiments of the dental instrument 1 depicted in FIGS. 5 and 6 show a protuberance 7 in the area of the upper part of the sleeve 3. This protuberance encloses the metal piece 4 of the drive means on both sides, as can be seen in FIG. 5, or only on its lower part, as is shown in FIG. 6. This protuberance permits capture of a force and/or a movement.

It will be appreciated from the above description that the dental instrument according to the invention is relatively simple to produce and permits greater resistance of the drive means.

Although the invention has been described in connection with two particular embodiments, it encompasses all technical equivalents of the means described. 

1. A mechanized dental instrument consisting of an active part (2) and of a sleeve (3) arranged at the end remote from said active part, said sleeve (3) of the dental instrument being provided with a rotary drive means (4) which, in a position mounted in a head of a handpiece, is able to mesh directly with a rotary drive means located upstream of the head of the handpiece, characterized in that the drive means (4) is produced from a flat metal piece which is fixed especially by being slid over the axle (2 a) of the active part (2), said piece being provided with at least one opening (5) shaped in such a way as to permit circulation of the plastic material forming the sleeve (3) during the phase of overmolding on said axle (2 a) and thus to ensure the connection of the rotary drive means on the axle (2 a).
 2. The mechanized dental instrument as claimed in claim 1, characterized in that the opening (5) is formed by the combination of flats (6) formed on the axle (2 a) of the active part (2) and the central orifice of the drive means (4).
 3. The mechanized dental instrument as claimed in claim 1 or 2, characterized in that the drive means (4) is produced from a flat piece whose toothing is formed by cutting and then, if appropriate, by bending.
 4. The mechanized dental instrument as claimed in one of the preceding claims, characterized in that the active part (2) extends right through the sleeve (3) from one end to the other.
 5. The mechanized dental instrument as claimed in one of the preceding claims, characterized in that the protuberance (7) of the upper part of the sleeve (3) captures a movement.
 6. The mechanized dental instrument as claimed in one of claims 1, 2, 3 and 4, characterized in that the protuberance (7) of the upper part of the sleeve (3) captures a force.
 7. The mechanized dental instrument as claimed in one of claims 1, 2, 3 and 4, characterized in that the protuberance (7) of the upper part of the sleeve (3) captures a movement and a force. 